Top leaders have told rescuers to race against time to save lives and do their best to resettle survivors following the earthquake in Yunnan province as the death toll from Sunday's disaster rose to nearly 400.

President Xi Jinping said on Sunday that saving lives is the top priority. He also called for the aftermath of the tragedy to be monitored.

Premier Li Keqiang walked for 5 km on muddy roads in Ludian county on Monday before arriving in Longquan, a village in Longtoushan township and the epicenter of the quake.

He stood in silent tribute to the victims, guided rescue efforts and comforted residents.

Sunday's magnitude-6.5 quake, which struck at 4:30 pm, killed at least 398 people and injured more than 1,900 others.

Heavy overnight rain made the mountainous county more difficult to reach, and Li slipped while walking along a muddy road.

On the flight to the disaster area on Monday morning, he said it was the most serious quake in the region in recent years.

The premier stressed that rescue efforts must progress in a scientific manner and urged rescuers to make full use of the "golden period" - the 72 hours since the quake took place - in their search efforts.

"With each life saved, there will be one more happy family," Li told soldiers in the township.

He told provincial authorities to keep access to the epicenter clear for rescue teams.

Shen Taikuan, a villager in Longtoushan, said, "My son was only found at midnight, but thank goodness he was not seriously injured." Shen carried his son on his back while talking to Li.

The premier asked Shen, as well as other injured people, to go to clinics and hospitals for checkups.

Liu Qiwei, an official at the county hospital, said it had treated at least 269 people, 10 of whom were seriously injured.

"Nearly 350 medical workers and 113 ambulances have been devoted to the rescue and additional beds have been provided," Liu said.

He added that supplies of relief materials and medicine to the disaster area must be speeded up to avoid the risk of disease posed by bodies lying in the debris. Liu also said that the safety of drinking water should be guaranteed.

Ma Wenxu, a Longtoushan resident, said the tiles on his house began to fall as the quake struck and he was afraid to stay at home.

"I slept in a car with my father. Ambulances' sirens were sounding throughout the night," Ma said.

The central government has allocated 600 million yuan ($97 million) for rescue efforts and more than 5,250 armed police officers and over 1,700 reserve forces have arrived at the county.

By Monday, 472 people had received medical treatment and 6,566 had been given shelter, the Ministry of National Defense said.

Provincial firefighters saved 32 residents on Monday, found 43 bodies and moved more than 1,800 residents to safer areas.

Zhang Li, who coordinates firefighters from Kunming, the provincial capital, said, "We called out more than 1,000 rescuers and 151 rescue vehicles across the province after the quake occurred."

The firefighters have been divided into three teams and sent to Ludian, Qiaojia and Huize counties, Zhang said.

Some rescue equipment, including cranes, could not be sent to the disaster area because of heavy traffic, he said, adding that the small number of firefighting teams need support from soldiers.

Some relief materials have been sent to seriously affected areas, including 20,000 tents, 30,000 quilts and 25,000 coats, the provincial civil affairs authority said.